/*
  将下面异步代码使用 Promise 的方法改进
  尽量用看上去像同步代码的方式
  setTimeout(function () {
    var a = 'hello'
    setTimeout(function () {
      var b = 'lagou'
      setTimeout(function () {
        var c = 'I ♥ U'
        console.log(a + b +c)
      }, 10)
    }, 10)
  }, 10)
*/
new Promise((resolve,reject) => {
      let a = 'hello'
    setTimeout(() => {
        resolve(a)
    }, 1000);
}).then(res => {
    return new Promise((resolve,reject) => {
        let b = 'hello'
        setTimeout(() => {
          resolve(res+b)
      }, 1000);
  })
}).then(res => {
    let c = 'I ♥ U'
    setTimeout(() => {
        console.log(res + c)
    }, 1000);
})